CYP2C19 and transient ischemic attack: In the group 2, there were 5 cases of stroke or transient ischemic attack within 230 days, including 3 cases of CYP2C19 gene deletion, 2 cases of CYP2C19 gene carriers, 2 cases of vertebrobasilar artery extracranial stenosis, and 3 cases of vertebrobasilar artery intracranial stenosis.